I own a business that is currently operating at 80% capacity and will likely continue at that level. I've received an offer from a multinational business that is offering me a contract that would require 30% of my existing capacity for each of the next 2 years. What should I ask them before making my decision?

What kind of business is this concerning, please? Knowing that would make a difference in the answers that you receive. I'm also not sure what you mean by "capacity" because we don't know what type of business this is concerning.

The business is involved with cosmetics, with lip care being one of our top sellers.